Plasma processsing method and apparatus thereof

ABSTRACT

A plasma processing method includes introducing a gas into a vacuum chamber through a hole of a dielectric tube attached to a metal body fixed to the vacuum chamber while exhausting from the vacuum chamber to keep the vacuum chamber within a specified pressure, and applying high-frequency power with a frequency ranging from 100 kHz to 3 GHz to a plasma source provided so as to face a substrate mounted on a substrate electrode in the vacuum chamber to generate plasmas in the vacuum chamber to perform plasma processing of the substrate.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a plasma processing method andan apparatus thereof for use in manufacturing electron devices and micromachines made of semiconductors and others.

[0002] In recent years, thin film processing technique using plasmaprocessing becomes more and more important in the field of manufacturingsemiconductor electron devices and micro machines.

[0003] As one example of prior art plasma processing methods, plasmaprocessing with use of an inductively coupled plasma source will bedescribed hereinbelow with reference to FIG. 8. In FIG. 8, a specifiedgas is introduced from a gas supply device 2 into a vacuum chamber 1while being exhausted therefrom by a pump 3 serving as an exhauster tokeep the vacuum chamber 1 within specified pressure. Under such acondition, high-frequency power of 13.56 MHz can be supplied by ahigh-frequency power source for coil 4 to a coil 23 to generate plasmasin the vacuum chamber 1 to perform plasma processing of a substrate 7mounted on a substrate electrode 6. In addition, there is provided ahigh-frequency power source for substrate electrode 8 for supplyinghigh-frequency power to the substrate electrode 6, which enables controlof ion energy reached the substrate 7. It is noted that the coil 23 isdisposed on top of a dielectric window 24. The gas is introduced intothe vacuum chamber 1 through a plurality of gas supply holes 25 providedon a metal ring 16 which constitutes part of a side wall of the vacuumchamber 1.

[0004] However, in order to improve fine processability and enlargeprocessing area, flow of gas to be used in processing should beincreased and processing should be performed under lower pressure, whichtends to induce abnormal electrical discharge called hollow cathodedischarge in gas supply holes 25 in the prior art plasma processing.

[0005] Description of the hollow cathode discharge is as follows. InGeneral, the surface of a solid in contact with plasmas is negativelyelectrified due to difference in thermal velocity between an electronand an ion, so that the solid surface obtains direct electric fieldswhich send away electrons from the solid surface. In a space surroundedwith the solid surface, like the inside of the gas supply hole 25 shownin the prior art, tendency to collision of electrons with the solidsurface is reduced due to the presence of the direct electric fields,which prolongs a lifetime of the electrons, resulting in generation ofhigh-density plasmas (for example, at 100 MHz) inside the gas supplyhole 25. Thus-generated electric discharge is called hollow cathodedischarge.

[0006] The hollow cathode discharge generated in the gas supply hole 25causes deterioration of the gas supply hole (the lapse of time causesgradual increase of the diameter of the hole) 25 and contamination of asubstrate by metal substances constituting the gas supply hole 25.

[0007] It is empirically indicated that larger gas velocity in the gassupply hole 25 and larger pressure gradient in the vicinity of the gassupply hole 25 tend to induce hollow cathode discharge. In addition,larger gas flow rate and lower pressure in the vacuum chamber 1 alsotends to induce hollow cathode discharge. Accordingly, improvement offine processability and implementation of larger processing area requirelarger flow rate of gas for use in processing and processing under lowerpressure, which clarifies importance of solving the issue of hollowcathode discharge in the gas supply hole 25.

SUMMARY OF THE INVENTION

[0008] In view of the conventional issue stated above, an object of thepresent invention is to provide a plasma processing method and anapparatus thereof which decreases induction of hollow cathode dischargein the gas supply hole.

[0009] In accomplishing these and other aspects, according to a firstaspect of the present invention, there is provided a plasma processingmethod comprising:

[0010] introducing a gas into a vacuum chamber through a hole of adielectric tube attached to a metal body fixed to the vacuum chamberwhile exhausting from the vacuum chamber to keep the vacuum chamberwithin a specified pressure; and

[0011] applying high-frequency power with a frequency ranging from 100kHz to 3 GHz to a plasma source provided so as to face a substratemounted on a substrate electrode in the vacuum chamber to generateplasmas in the vacuum chamber to perform plasma processing of thesubstrate.

[0012] According to a aspect of the present invention, there is provideda plasma processing method as defined in the first aspect, wherein thehigh-frequency power with a frequency ranging from 100 kHz to 3 GHz isapplied to an antenna serving as the plasma source with a dielectricplate interposed between the antenna and the vacuum chamber and with theantenna and the dielectric plate protruded in the vacuum chamber.

[0013] According to a second aspect of the present invention, there isprovided a plasma processing method as defined in the first aspect,wherein the high-frequency power is applied to an antenna serving as theplasma source through a penetrating hole given near a center of thedielectric plate with the antenna and the vacuum chamber short-circuitedwith short pins through penetrating holes which are given at an arealocated not in a center nor a vicinity of the dielectric plate and whichare disposed at approximately equal intervals around a center of theantenna.

[0014] According to a third aspect of the present invention, there isprovided a plasma processing method as defined in the first aspect,wherein a substrate is processed in a state that a plasma distributionon the substrate is controlled by a circular and groove shaped plasmatrap provided between the antenna and the vacuum chamber.

[0015] According to a fourth aspect of the present invention, there isprovided a plasma processing method as defined in the first aspect,wherein a substrate is processed in a state that a plasma distributionon the substrate is controlled by a groove shaped plasma trap providedbetween the antenna and the metal body which is a ring disposed so as toconstitute the plasma trap therebetween.

[0016] According to a fifth aspect of the present invention, there isprovided a plasma processing method comprising:

[0017] introducing a gas into a vacuum chamber through a hole of adielectric tube attached to a facing electrode provided so as to face asubstrate electrode in the vacuum chamber while exhausting from thevacuum chamber to keep the vacuum chamber within a specified pressure;and

[0018] applying high-frequency power with a frequency ranging from 100kHz to 3 GHz to the substrate electrode or the facing electrode togenerate plasmas in the vacuum chamber to perform plasma processing ofthe substrate.

[0019] According to a sixth aspect of the present invention, there isprovided a plasma processing method as defined in the first aspect,wherein gas supply flow rate per hole given to the dielectric tube is200 sccm or less.

[0020] According to a seventh aspect of the present invention, there isprovided a plasma processing method as defined in the first aspect,wherein gas supply flow rate per hole given to the dielectric tube is 50sccm or less.

[0021] According to an eighth aspect of the present invention, there isprovided a plasma processing method as defined in the first aspect,wherein the gas is a mixed gas mainly composed of an argon gas.

[0022] According to a ninth aspect of the present invention, there isprovided a plasma processing method as defined in the first aspect,wherein pressure in the vacuum chamber is 10 Pa or less.

[0023] According to a 10th aspect of the present invention, there isprovided a plasma processing method as defined in the first aspect,wherein pressure in the vacuum chamber is 1 Pa or less.

[0024] According to an 11th aspect of the present invention, there isprovided a plasma processing method as defined in the first aspect,wherein a frequency of the high-frequency power applied to the plasmasource, the substrate electrode or the facing electrode is 50 MHz to 3GHz.

[0025] According to a 12th aspect of the present invention, there isprovided a plasma processing method as defined in the sixth aspect,wherein gas supply flow rate per hole given to the dielectric tube is200 sccm or less.

[0026] According to a 13th aspect of the present invention, there isprovided a plasma processing method as defined in the sixth aspect,wherein gas supply flow rate per hole given to the dielectric tube is 50sccm or less.

[0027] According to a 14th aspect of the present invention, there isprovided a plasma processing method as defined in the sixth aspect,wherein the gas is a mixed gas mainly composed of an argon gas.

[0028] According to a 15th aspect of the present invention, there isprovided a plasma processing method as defined in the sixth aspect,wherein pressure in the vacuum chamber is 10 Pa or less.

[0029] According to a 16th aspect of the present invention, there isprovided a plasma processing method as defined in the sixth aspect,wherein pressure in the vacuum chamber is 1 Pa or less.

[0030] According to a 17th aspect of the present invention, there isprovided a plasma processing method as defined in the sixth aspect,wherein a frequency of the high-frequency power applied to the plasmasource, the substrate electrode or the facing electrode is 50 MHz to 3GHz.

[0031] According to an 18th aspect of the present invention, there isprovided a plasma processing apparatus comprising:

[0032] a vacuum chamber capable of maintaining a vacuum state;

[0033] a gas supply device for supplying a gas into the vacuum chamber;

[0034] an exhauster for exhausting the gas from the vacuum chamber;

[0035] a substrate electrode for mounting a substrate in the vacuumchamber;

[0036] a plasma source provided so as to face the substrate electrode;

[0037] a high-frequency power source for supplying high-frequency powerwith a frequency ranging from 100 kHz to 3 GHz to the plasma source; and

[0038] a dielectric tube having a gas supply hole, attached to a metalbody fixed to the vacuum chamber, for passing the gas through the gassupply hole thereof when the gas is supplied to the vacuum chamber bythe gas supply device.

[0039] According to a 19th aspect of the present invention, there isprovided a plasma processing apparatus as defined in the 18th aspect,wherein a dielectric plate is interposed between the vacuum chamber andan antenna serving as the plasma source, and the antenna and thedielectric plate are protruded in the vacuum chamber.

[0040] According to a 20th aspect of the present invention, there isprovided a plasma processing apparatus as defined in the 19th aspect,wherein high-frequency power is supplied to the antenna through apenetrating hole given near a center of the dielectric plate, and theantenna and the vacuum chamber are short-circuited with short pinsthrough penetrating holes which are given at an area located not in acenter nor a vicinity of the dielectric plate and which are disposed atapproximately equal intervals around a center of the antenna.

[0041] According to a 21st aspect of the present invention, there isprovided a plasma processing apparatus as defined in the 19th aspect,wherein a substrate is processed in a state that a plasma distributionon the substrate is controlled by a circular and groove shaped plasmatrap provided between the antenna and the vacuum chamber.

[0042] According to a 22nd aspect of the present invention, there isprovided a plasma processing apparatus as defined in the 18th aspect,wherein the metal body is a ring that constitutes a part of a side wallof the vacuum chamber.

[0043] According to a 23rd aspect of the present invention, there isprovided a plasma processing apparatus as defined in the 21st aspect,wherein the metal body is a ring disposed so as to constitute a plasmatrap between the metal body and the antenna.

[0044] According to a 24th aspect of the present invention, there isprovided a plasma processing apparatus comprising:

[0045] a vacuum chamber capable of maintaining a vacuum state;

[0046] a gas supply device for supplying a gas into the vacuum chamber;

[0047] an exhauster for exhausting the gas from the vacuum chamber;

[0048] a substrate electrode for mounting a substrate in the vacuumchamber;

[0049] a facing electrode provided so as to face the substrateelectrode;

[0050] a high-frequency power source for supplying high-frequency powerwith a frequency ranging from 100 kHz to 3 GHz to the substrateelectrode or the facing electrode;

[0051] a dielectric tube having a gas supply hole, attached to a metalbody fixed to the facing electrode, for passing the gas through the gassupply hole thereof when the gas is supplied to the vacuum chamber bythe gas supply device.

[0052] According to a 25th aspect of the present invention, there isprovided a plasma processing apparatus as defined in the 18th aspect,wherein the dielectric tube is a bolt screwed in a tap given to themetal body or the facing electrode.

[0053] According to a 26th aspect of the present invention, there isprovided a plasma processing apparatus as defined in the 18th aspect,wherein the dielectric tube has a spot facing for screwdriver or wrenchon a side of an inner wall of the vacuum chamber for rotating andscrewing the dielectric tube in the metal plate or the facing electrode.

[0054] According to a 27th aspect of the present invention, there isprovided a plasma processing apparatus as defined in the 18th aspect,wherein the dielectric tube is protruded by 0.5 to 20 mm from a surfaceof the metal body or the facing electrode.

[0055] According to a 28th aspect of the present invention, there isprovided a plasma processing apparatus as defined in the 18th aspect,wherein the dielectric tube is protruded by 1 to 10 mm from a surface ofthe metal body or the facing electrode.

[0056] According to a 29th aspect of the present invention, there isprovided a plasma processing apparatus as defined in the 27th or 28thaspect, wherein the dielectric tube is disposed such that it covers anedge of a hole of the metal body or the facing electrode.

[0057] According to a 30th aspect of the present invention, there isprovided a plasma processing apparatus as defined in the 18th aspect,wherein the hole of the dielectric tube is 0.2 to 2 mm in diameter.

[0058] According to a 31st aspect of the present invention, there isprovided a plasma processing apparatus as defined in the 18th aspect,wherein the hole of the dielectric tube is 0.4 to 0.8 mm in diameter.

[0059] According to a 32nd aspect of the present invention, there isprovided a plasma processing apparatus as defined in the 18th aspect,wherein a frequency of high-frequency power applied to the plasmasource, the substrate electrode or the facing electrode is 50 MHz to 3GHz.

[0060] According to a 33rd aspect of the present invention, there isprovided a plasma processing apparatus as defined in the 24th aspect,wherein the dielectric tube is a bolt screwed in a tap given to themetal body or the facing electrode.

[0061] According to a 34th aspect of the present invention, there isprovided a plasma processing apparatus as defined in the 24th aspect,wherein the dielectric tube has a spot facing for screwdriver or wrenchon a side of an inner wall of the vacuum chamber for rotating andscrewing the dielectric tube in the metal plate or the facing electrode.

[0062] According to a 35th aspect of the present invention, there isprovided a plasma processing apparatus as defined in the 24th aspect,wherein the dielectric tube is protruded by 0.5 to 20 mm from a surfaceof the metal body or the facing electrode.

[0063] According to a 36th aspect of the present invention, there isprovided a plasma processing apparatus as defined in the 24th aspect,wherein the dielectric tube is protruded by 1 to 10 mm from a surface ofthe metal body or the facing electrode.

[0064] According to a 37th aspect of the present invention, there isprovided a plasma processing apparatus as defined in the 27th or 28thaspect, wherein the dielectric tube is disposed such that it covers anedge of a hole of the metal body or the facing electrode.

[0065] According to a 38th aspect of the present invention, there isprovided a plasma processing apparatus as defined in the 24th aspect,wherein the hole of the dielectric tube is 0.2 to 2 mm in diameter.

[0066] According to a 39th aspect of the present invention, there isprovided a plasma processing apparatus as defined in the 24th aspect,wherein the hole of the dielectric tube is 0.4 to 0.8 mm in diameter.

[0067] According to a 40th aspect of the present invention, there isprovided a plasma processing apparatus as defined in the 24th aspect,wherein a frequency of high-frequency power applied to the plasmasource, the substrate electrode or the facing electrode is 50 MHz to 3GHz.

BRIEF DESCRIPTION OF THE DRAWINGS

[0068] These and other aspects and features of the present inventionwill become clear from the following description taken in conjunctionwith the preferred embodiments thereof with reference to theaccompanying drawings, in which:

[0069]FIG. 1 is a cross sectional view showing construction of a plasmaprocessing apparatus for use in a first embodiment of the presentinvention;

[0070]FIG. 2 is a detail view showing the vicinity of a dielectric bushfor use in the first embodiment of the present invention;

[0071]FIG. 3 is a plane view showing an antenna for use in the firstembodiment of the present invention;

[0072]FIG. 4 is a cross sectional view showing construction of a casewhere the present invention is applied to a plasma processing apparatuswith a surface wave plasma source;

[0073]FIG. 5 is a cross sectional view showing construction of theplasma processing apparatus in a modified example of the firstembodiment of the present invention;

[0074]FIG. 6 is a cross sectional view showing construction of a plasmaprocessing apparatus for use in a second embodiment of the presentinvention;

[0075]FIG. 7 is a detail view showing the vicinity of a dielectric bushfor use in the second embodiment of the present invention;

[0076]FIG. 8 is a cross sectional view showing construction of a plasmaprocessing apparatus for use in the prior art;

[0077]FIG. 9 is a perspective view of the dielectric bush according tothe first embodiment;

[0078]FIG. 10 is a sectional view of a dielectric bush according to afirst modification of the first embodiment;

[0079]FIG. 11 is a sectional view of a dielectric bush according to asecond modification of the first embodiment;

[0080]FIG. 12 is a sectional view of a dielectric bush according to athird modification of the first embodiment;

[0081]FIG. 13 is a perspective view of the dielectric bush according tothe third modification of the first embodiment; and

[0082]FIG. 14 is a sectional view of a dielectric bush according to afourth modification of the first embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0083] Before the description of the present invention proceeds, it isto be noted that like parts are designated by like reference numeralsthroughout the accompanying drawings.

[0084] Description will now be given of the first embodiment of thepresent invention with reference to FIGS. 1 to 3.

[0085]FIG. 1 shows a cross sectional view of a plasma processingapparatus for use in the first embodiment of the present invention. InFIG. 1, a specified gas is introduced from a gas supply device 2 into avacuum chamber 1 while being exhausted therefrom by a pump 3 serving asan example of an exhauster to keep the vacuum chamber 1 within aspecified pressure. Under such a condition, high-frequency power of 100MHz can be supplied by a high-frequency power source for antenna 4 to anantenna 5, as one example of a plasma source, protruded into the vacuumchamber 1 to generate plasmas in the vacuum chamber 1 to perform plasmaprocessing of a substrate 7 mounted on a substrate electrode 6. Inaddition, there is provided a high-frequency power source for substrateelectrode 8 for supplying high-frequency power to the substrateelectrode 6, which enables control of ion energy reached the substrate7. High-frequency voltages supplied to the antenna 5 is guided by a feedbar 9 to a central part of the antenna 5. A plurality of areas locatednot in the center nor the vicinity of the antenna 5 and a plane 1Afacing the substrate 7 of the vacuum chamber 1 are short-circuited byshort pins 10. A dielectric plate 11 is interposed between the antenna 5and the vacuum chamber 1. Through penetrating holes provided on thedielectric plate 11, the feed bar 9 and the short pins 10 connect theantenna 5 to the high-frequency power source for antenna 4 and theantenna 5 to a vacuum chamber 1, respectively. The surface of theantenna 5 is covered with an insulative cover 12. There is provided aplasma trap 15 made up of a groove-shaped space between the dielectricplate 11 and a dielectric ring 13 placed in the vicinity of thedielectric plate 11, and a groove-shaped space between the antenna 5 anda conduction ring 14 placed in the vicinity of the antenna 5. By the gassupply device 2, the gas is introduced into the vacuum chamber 1 througha gas supply hole 18 (See FIG. 2) provided on a dielectric bush 17, asone example of a dielectric tube, attached to a metal ring 16 whichconstitutes a part of a side wall of the vacuum chamber 1 and has aring-shaped gas passage 16 a therein and is made of metal such asaluminum or stainless steel.

[0086]FIG. 2 shows a detail view around the dielectric bush 17 made ofceramic as one example. On the side of the inner wall of the vacuumchamber 1, there is provided a spot facing for screw driver 19 (See FIG.9) for rotating and screwing the dielectric bush 17 in the metal ring16. The metal ring 16 is equipped with a tap 20 for screwing in thedielectric bush 17. The dielectric bush 17 has the shape of a bolt. Thedielectric bush 17 is protruded by 5 mm from the surface of the metalring 16. The dielectric bush 17 is disposed such that it covers an edge21 of a hole provided on the metal ring 16. A gas supply hole 18 givenon the dielectric bush 17 is 0.5 mm in diameter. The metal ring 16 isequipped with total 8 dielectric bushes 17, making it possible to blowout gas into the vacuum chamber 1 in approximately isotropic direction.FIG. 3 shows a plane view of the antenna 5. In FIG. 3, the short pins 10are put in three locations. Each of three short pins 10 is disposed atequal intervals around the center of the antenna 5.

[0087] With the plasma processing apparatus shown in FIGS. 1 to 3, asubstrate having an iridium film was etched. Etching was conducted underthe conditions of argon gas of 260 sccm and chlorine gas of 20 sccm,pressure of 0.3 Pa, antenna power of 1500 W, and substrate electrodepower of 400 W. Total gas flow rate was 260+20=280 sccm, and the numberof gas supply holes was 8, so that gas supply flow rate per gas supplyhole was 280/8=35 sccm. As a result of etching under such conditions,hollow cathode discharge in each gas supply hole 18 did not occur, andtherefore good discharge condition was obtained.

[0088] The reason why the hollow cathode discharge could be suppressedmay be that high-frequency electric fields in each gas supply hole 18were weakened compared to those in the prior art example. It can beconsidered that an inclination to occurrence of the hollow cathodedischarge is largely influenced by high-frequency electric fieldsreached the gas supply holes as well as gas velocity or pressuregradient. It can be considered that composing the vicinity of each gassupply hole 18 of a dielectric substance and protruding the dielectricbush 17 by 5 mm from the surface of the metal ring 16 weakenhigh-frequency electric fields in an outlet of each gas supply hole 18,thereby enabling suppression of the hollow cathode discharge.

[0089] The above-described first embodiment of the present invention isjust one example of a number of variations available in the shape of thevacuum chamber as well as the shape and disposition of the antennawithin an applicable range of the present invention. It will beunderstood that diverse variations other than the one exemplified hereabove are available in application of the present invention.

[0090] In the above described first embodiment of the present invention,high-frequency voltage is supplied to the antenna through a penetratinghole given near the center of the dielectric plate, and the antenna andthe vacuum chamber are short-circuited with the short pins throughpenetrating holes which are given at an area located not in the centernor the vicinity of the dielectric plate and which are disposed atapproximately equal intervals around the center of the antenna. Suchconstruction makes it possible to increase isotropy of plasmas. In thecase of handling a small substrate, the present invention ensuressufficiently high inplane uniformity without use of the short pins.

[0091] Further, in the first embodiment of the present invention, therehas been described the case of processing the substrate in the statethat the plasma distribution on to the substrate was controlled by thecircular and groove shaped plasma trap provided between the antenna andthe vacuum chamber. Such construction contributes to increase uniformityof plasmas. In the case of handling a small substrate, the presentinvention ensures sufficiently high inplane uniformity without use ofthe plasma trap.

[0092] The present invention is also effective when using as an antennathe coil 23 in the case with the inductively coupled plasma source shownin FIG. 8 describing the prior art example or an electromagneticradiation antenna 26 in the case with a surface wave plasma source shownin FIG. 4.

[0093] Further in the first embodiment of the present invention shownabove, the metal body with the dielectric bush embedded is the ring thatconstitutes a part of the side wall of the vacuum chamber. Suchconstruction is also effective when, as shown in FIG. 5, a metal bodywith a dielectric bush embedded is a conduction ring 14 disposed so asto constitute a plasma trap between the metal body and the antenna.

[0094] Description will now be given of a second embodiment of thepresent invention with reference to FIGS. 6 to 7.

[0095]FIG. 6 is a cross sectional view of a plasma processing apparatusfor use in the second embodiment of the present invention. In FIG. 6, aspecified gas is introduced from a gas supply device 2 into a vacuumchamber 1 while being exhausted therefrom by a pump 3 serving as anexample of an exhauster to keep the vacuum chamber 1 within a specifiedpressure. Under such a condition, high-frequency power of 13.56 MHz canbe supplied by a high-frequency power source for substrate electrode 8to a substrate electrode 6 to generate plasmas in the vacuum chamber 1to perform plasma processing of a substrate 7 mounted on a substrateelectrode 6. There is provided a facing electrode 22 that faces thesubstrate electrode 6 and has therein a gas passage 22 a connected to aplurality of holes with taps 20. The gas is introduced into the vacuumchamber 1 through a gas supply hole 18 (See FIG. 7) given to adielectric bush 17, as one example of a dielectric tube, placed on thefacing electrode 22.

[0096]FIG. 7 shows a detail view around the dielectric bush 17 made ofceramic as one example. On the side of the inner wall of the vacuumchamber 1, the dielectric bush 17 has a spot facing for screw driver 19(See FIG. 9) for rotating and screwing the dielectric bush 17 in thefacing electrode 22. The facing electrode 22 is equipped with a tap 20for screwing in the dielectric bush 17. The dielectric bush 17 has theshape of a bolt. The dielectric bush 17 is protruded by 5 mm from thesurface of the facing electrode 22. The dielectric bush 17 is disposedsuch that it covers an edge 21 of a hole provided on the facingelectrode 22. A gas supply hole 18 given on the dielectric bush 17 is0.5 mm in diameter. The facing electrode 22 is equipped with total 80dielectric bushes 17, making it possible to blow out gas toward asubstrate in the vacuum chamber 1.

[0097] With the plasma processing apparatus shown in FIGS. 6 to 7, asubstrate having an aluminum film was etched. Etching was conductedunder the conditions of chlorine gas of 200 sccm, boron trichloride gasof 600 sccm, argon gas 800 sccm, pressure of 5 Pa, and substrateelectrode power of ∝kW. Total gas flow rate was 200+600+800=1600 sccm,and the number of gas supply holes was 80, so that gas supply flow rateper gas supply hole was 1600/80=20 sccm. As a result of etching undersuch conditions, hollow cathode discharge in each gas supply hole 18 didnot occur, and therefore good discharge condition was obtained.

[0098] The reason why the hollow cathode discharge could be suppressedmay be that high-frequency electric fields in each gas supply hole 18were weakened compared to those in the prior art example. It can beconsidered that an inclination to occurrence of the hollow cathodedischarge is largely influenced by high-frequency electric fieldsreached the gas supply holes as well as gas velocity or pressuregradient. It can be considered that composing the vicinity of each gassupply hole 18 of a dielectric substance and protruding the dielectricbush 17 by 5 mm from the surface of the facing electrode 22 weakenhigh-frequency electric fields in an outlet of each gas supply hole 18,thereby enabling suppression of the hollow cathode discharge.

[0099] In the above described embodiments of the present invention, thedielectric bush is a bolt screwed in the tap given to the metal body orthe facing electrode. However, the dielectric bush is not necessarily inthe shape of a bolt, but may be embedded to the metal body or the facingelectrode in the shape of a wedge. The dielectric bush in the shape of abolt has an advantage that replacement thereof as an expendablecomponent is easy.

[0100] Further, there has been described that the dielectric bush had aspot facing for screw driver on the side of the inner wall of the vacuumchamber for rotating and screwing the dielectric bush in the metal plateor the facing electrode. However, other than the spot facing for screwdriver, the present invention may adopt shapes for various tools such aswrenches. It goes without saying that the spot facing is not necessaryif the dielectric bush is wedge-shaped.

[0101] As described above, the dielectric bush is protruded by 5 mm fromthe surface of the metal body or the facing electrode. Since anexperimental result proves that approx. 0.5 mm or more protrusion isdesirable, the length of protrusion of the dielectric bush is preferablywithin this range. However, excessive protrusion may lead to breakage ofthe dielectric bush, and therefore the dielectric bush may preferably beprotruded by approx. 20 mm or less. Accordingly, an optimum length ofprotrusion of the dielectric bush is considered to be about 1 to 10 mm,which surely ensures suppression of hollow cathode discharge andprevents breakage of the dielectric bush.

[0102] As described above, the dielectric bush is disposed such that itcovers the edge of the hole provided on the metal body or the facingelectrode. Such construction is preferable since it can effectivelyprevent the edge of the hole provided on the metal body or the facingelectrode from deteriorating due to exposure to plasmas for a longperiod of time.

[0103] As described above, the hole given on the dielectric bush is 0.5mm in diameter. Since an experimental result proves that a smaller holereduces a tendency to occurrence of hollow cathode discharge, the sizeof the hole is preferably about 2 mm or less. However too small a holeincreases difficulty in processability, and therefore the diameter ofthe hole is preferably 0.2 mm or more. Accordingly, an optimum diameterof the hole is considered to be about 0.4 to 0.8 mm, which ensuressuppression of hollow cathode discharge and facilitates processing.

[0104] There were described the cases where the gas supply flow rate perhole given to the dielectric bush was 35 sccm and 20 sccm. Since anexperimental result proves that smaller gas supply flow rate per holereduces a tendency to occurrence of hollow cathode discharge, gas supplyflow rate per hole is preferably around 200 sccm or less. For moresecure suppression of hollow cathode discharge, gas supply flow rate perhole given to the dielectric bush is preferably 50 sccm or less. Tomeets such conditions, increase of the number of the gas supply holes iseffective as well as decrease of gas flow rate in plasma processing.

[0105] As described above, a gas for use in the present invention is amixed gas mainly composed of an argon gas. It is empirically proved thata tendency to occurrence of hollow cathode discharge differs by types ofgases, and an argon gas considerably increases the tendency.Accordingly, the present invention is particularly effective when amixed gas mainly composed of an argon gas is in use. In the case ofusing other gases, the present invention is also quite effective forsuppression of hollow cathode discharge.

[0106] There were also described the cases where the pressure in thevacuum chamber was 0.3 Pa and 5 Pa. Since lower pressure in the vacuumchamber increases a tendency to occurrence of hollow cathode discharge,the present invention is effective when the pressure in the vacuumchamber is 10 Pa or less. The present invention is further effectivewhen the pressure in the vacuum chamber is 1 Pa or less.

[0107] There were described the cases where a frequency ofhigh-frequency power applied to the antenna, the substrate electrode orthe facing electrode was 100 MHz or 13.56 MHz. In plasma processing withlow pressure, there can be used high-frequency power ranging from 100kHz to 3 GHz, and over such a broad range, the present invention iseffective. However, with a higher frequency of high-frequency power,electromagnetic waves tend to spread in a wider range, which tends toincrease high-frequency electric fields in the gas supply hole.Accordingly, the present invention is effective when a frequency of highfrequency power is high, especially in the range from 50 MHz to 3 GHz.

[0108]FIG. 10 is a sectional view of a dielectric bush 17A according toa first modification of the first embodiment. The dielectric bush 17Ahas a spot facing 17 g at the inner end side thereof with the diameterof the spot facing lager than the diameter of the gas supply hole 18 andwith the spot facing 17 g connected to the gas passage 16 a. Thedistance of the gas supply hole 18 is not less than 1 mm, preferably, soas to surely obtain the above effects.

[0109]FIG. 11 is a sectional view of a dielectric bush 17B according toa second modification of the first embodiment where the dielectric bush17B is not protruded from the surface of the metal ring 16 in a casewhere Ar gas and the antenna power of 500 W or less are used.

[0110]FIGS. 12 and 13 are a sectional view and a perspective view of adielectric bush 17C according to a third modification of the firstembodiment where the dielectric bush 17C has a projection 17 h, insteadof a screw portion, for engaging with a recess 16 h. The projection 17 hcan pass through a groove 16 j of the metal ring 16 and then thedielectric bush 17C is rotated to engage the projection 17 h with therecess 16 h, so that the dielectric bush 17C is not taken out from themetal ring 16 in its axial direction. When the dielectric bush 17C istaken out from the metal ring 16, the dielectric bush 17C is rotated toinsert the projection 17 h into the groove 16 j, so that the dielectricbush 17C is taken out from the metal ring 16 in its axial direction.

[0111]FIG. 14 is a sectional view of a dielectric bush 17D according toa fourth modification of the first embodiment where the whole of thedielectric bush 17D is protruded from the surface of the metal ring 16with the gas supply hole 18 connected to a gas hole 16 i of the metalring 16.

[0112] As is clear from the above description, according to the plasmaprocessing method in the present invention, the gas is introduced intothe vacuum chamber while being exhausted therefrom to keep the vacuumchamber within a specified pressure. Under such a condition,high-frequency power with a frequency ranging from 100 kHz to 3 GHz isapplied to the plasma source such as the antenna provided so as to facethe substrate mounted on the substrate electrode in the vacuum chamberto generate plasmas in the vacuum chamber to perform plasma processingof the substrate. In this method, the gas is supplied to the vacuumchamber through the hole given to the dielectric bush embedded in themetal body, which implements plasma processing that reduces a tendencyto occurrence of hollow cathode discharge in the gas supply hole.

[0113] According to the plasma processing method in the presentinvention, the gas is introduced into the vacuum chamber while beingexhausted therefrom to keep the vacuum chamber within a specifiedpressure. Under such a condition, high-frequency power with a frequencyranging from 100 kHz to 3 GHz is applied to the substrate electrode orthe facing electrode provided so as to face the substrate electrode inthe vacuum chamber to generate plasmas in the vacuum chamber to performplasma processing of a substrate mounted on the substrate electrode. Inthis method, the gas is supplied to the vacuum chamber through the holegiven to the dielectric bush embedded in the facing electrode, whichimplements plasma processing that reduces a tendency to occurrence ofhollow cathode discharge in the gas supply hole.

[0114] According to the plasma processing apparatus in the presentinvention, the plasma processing apparatus is made up of the vacuumchamber, the gas supply device for supplying the gas into the vacuumchamber, the exhauster for exhausting the gas from the vacuum chamber,the substrate electrode for mounting the substrate in the vacuumchamber, the plasma source such as the antenna provided so as to facethe substrate electrode, and the high-frequency power source forsupplying high-frequency power with a frequency ranging from 100 kHz to3 GHz to the antenna. In this device, the gas is supplied to the vacuumchamber through the hole given to the dielectric bush embedded in themetal body, which implements plasma processing that reduces a tendencyto occurrence of hollow cathode discharge in the gas supply hole.

[0115] According to the plasma processing apparatus in the presentinvention, the plasma processing apparatus is made up of the vacuumchamber, the gas supply device for supplying the gas into the vacuumchamber, the exhauster for exhausting the gas from the vacuum chamber,the substrate electrode for mounting the substrate in the vacuumchamber, the facing electrode provided so as to face the substrateelectrode, and the high-frequency power source for supplyinghigh-frequency power with a frequency ranging from 100 kHz to 3 GHz tothe substrate electrode or the facing electrode. In this device, the gasis supplied to the vacuum chamber through the hole given to thedielectric bush embedded in the facing electrode, which implementsplasma processing that reduces a tendency to occurrence of hollowcathode discharge in the gas supply hole.

[0116] Although the present invention has been fully described inconnection with the preferred embodiments thereof with reference to theaccompanying drawings, it is to be noted that various changes andmodifications are apparent to those skilled in the art. Such changes andmodifications are to be understood as included within the scope of thepresent invention as defined by the appended claims unless they departtherefrom.

What is claimed is:
 1. A plasma processing method comprising:introducing a gas into a vacuum chamber through a hole of a dielectrictube attached to a metal body fixed to the vacuum chamber whileexhausting from the vacuum chamber to keep the vacuum chamber within aspecified pressure; and applying high-frequency power with a frequencyranging from 100 kHz to 3 GHz to a plasma source provided so as to facea substrate mounted on a substrate electrode in the vacuum chamber togenerate plasmas in the vacuum chamber to perform plasma processing ofthe substrate.
 2. A plasma processing method as defined in claim 1,wherein the high-frequency power is applied to an antenna serving as theplasma source through a penetrating hole given near a center of thedielectric plate with the antenna and the vacuum chamber short-circuitedwith short pins through penetrating holes which are given at an arealocated not in a center nor a vicinity of the dielectric plate and whichare disposed at approximately equal intervals around a center of theantenna.
 3. A plasma processing method as defined in claim 1, wherein asubstrate is processed in a state that a plasma distribution on thesubstrate is controlled by a circular and groove shaped plasma trapprovided between the antenna and the vacuum chamber.
 4. A plasmaprocessing method as defined in claim 1, wherein a substrate isprocessed in a state that a plasma distribution on the substrate iscontrolled by a groove shaped plasma trap provided between the antennaand the metal body which is a ring disposed so as to constitute theplasma trap therebetween.
 5. A plasma processing method comprising:introducing a gas into a vacuum chamber through a hole of a dielectrictube attached to a facing electrode provided so as to face a substrateelectrode in the vacuum chamber while exhausting from the vacuum chamberto keep the vacuum chamber within a specified pressure; and applyinghigh-frequency power with a frequency ranging from 100 kHz to 3 GHz tothe substrate electrode or the facing electrode to generate plasmas inthe vacuum chamber to perform plasma processing of the substrate.
 6. Aplasma processing method as defined in claim 1, wherein gas supply flowrate per hole given to the dielectric tube is 200 sccm or less.
 7. Aplasma processing method as defined in claim 1, wherein gas supply flowrate per hole given to the dielectric tube is 50 sccm or less.
 8. Aplasma processing method as defined in claim 1, wherein the gas is amixed gas mainly composed of an argon gas.
 9. A plasma processing methodas defined in claim 1, wherein pressure in the vacuum chamber is 10 Paor less.
 10. A plasma processing method as defined in claim 1, whereinpressure in the vacuum chamber is 1 Pa or less.
 11. A plasma processingmethod as defined in claim 1, wherein a frequency of the high-frequencypower applied to the plasma source, the substrate electrode or thefacing electrode is 50 MHz to 3 GHz.
 12. A plasma processing method asdefined in claim 6, wherein gas supply flow rate per hole given to thedielectric tube is 200 sccm or less.
 13. A plasma processing method asdefined in claim 6, wherein gas supply flow rate per hole given to thedielectric tube is 50 sccm or less.
 14. A plasma processing method asdefined in claim 6, wherein the gas is a mixed gas mainly composed of anargon gas.
 15. A plasma processing method as defined in claim 6, whereinpressure in the vacuum chamber is 10 Pa or less.
 16. A plasma processingmethod as defined in claim 6, wherein pressure in the vacuum chamber is1 Pa or less.
 17. A plasma processing method as defined in claim 6,wherein a frequency of the high-frequency power applied to the plasmasource, the substrate electrode or the facing electrode is 50 MHz to 3GHz.
 18. A plasma processing apparatus comprising: a vacuum chambercapable of maintaining a vacuum state; a gas supply device for supplyinga gas into the vacuum chamber; an exhauster for exhausting the gas fromthe vacuum chamber; a substrate electrode for mounting a substrate inthe vacuum chamber; a plasma source provided so as to face the substrateelectrode; a high-frequency power source for supplying high-frequencypower with a frequency ranging from 100 kHz to 3 GHz to the plasmasource; and a dielectric tube having a gas supply hole, attached to ametal body fixed to the vacuum chamber, for passing the gas through thegas supply hole thereof when the gas is supplied to the vacuum chamberby the gas supply device.
 19. A plasma processing apparatus as definedin claim 18, wherein a dielectric plate is interposed between the vacuumchamber and an antenna serving as the plasma source, and the antenna andthe dielectric plate are protruded in the vacuum chamber.
 20. A plasmaprocessing apparatus as defined in claim 19, wherein high-frequencypower is supplied to the antenna through a penetrating hole given near acenter of the dielectric plate, and the antenna and the vacuum chamberare short-circuited with short pins through penetrating holes which aregiven at an area located not in a center nor a vicinity of thedielectric plate and which are disposed at approximately equal intervalsaround a center of the antenna.
 21. A plasma processing apparatus asdefined in claim 19, wherein a substrate is processed in a state that aplasma distribution on the substrate is controlled by a circular andgroove shaped plasma trap provided between the antenna and the vacuumchamber.
 22. A plasma processing apparatus as defined in claim 18,wherein the metal body is a ring that constitutes a part of a side wallof the vacuum chamber.
 23. A plasma processing apparatus as defined inclaim 21, wherein the metal body is a ring disposed so as to constitutea plasma trap between the metal body and the antenna.
 24. A plasmaprocessing apparatus comprising: a vacuum chamber capable of maintaininga vacuum state; a gas supply device for supplying a gas into the vacuumchamber; an exhauster for exhausting the gas from the vacuum chamber; asubstrate electrode for mounting a substrate in the vacuum chamber; afacing electrode provided so as to face the substrate electrode; ahigh-frequency power source for supplying high-frequency power with afrequency ranging from 100 kHz to 3 GHz to the substrate electrode orthe facing electrode; a dielectric tube having a gas supply hole,attached to a metal body fixed to the facing electrode, for passing thegas through the gas supply hole thereof when the gas is supplied to thevacuum chamber by the gas supply device.
 25. A plasma processingapparatus as defined in claim 18, wherein the dielectric tube is a boltscrewed in a tap given to the metal body or the facing electrode.
 26. Aplasma processing apparatus as defined in claim 18, wherein thedielectric tube has a spot facing for screwdriver or wrench on a side ofan inner wall of the vacuum chamber for rotating and screwing thedielectric tube in the metal plate or the facing electrode.
 27. A plasmaprocessing apparatus as defined in claim 18, wherein the dielectric tubeis protruded by 0.5 to 20 mm from a surface of the metal body or thefacing electrode.
 28. A plasma processing apparatus as defined in claim18, wherein the dielectric tube is protruded by 1 to 10 mm from asurface of the metal body or the facing electrode.
 29. A plasmaprocessing apparatus as defined in claim 27 or 28, wherein thedielectric tube is disposed such that it covers an edge of a hole of themetal body or the facing electrode.
 30. A plasma processing apparatus asdefined in claim 18, wherein the hole of the dielectric tube is 0.2 to 2mm in diameter.
 31. A plasma processing apparatus as defined in claim18, wherein the hole of the dielectric tube is 0.4 to 0.8 mm indiameter.
 32. A plasma processing apparatus as defined in claim 18,wherein a frequency of high-frequency power applied to the plasmasource, the substrate electrode or the facing electrode is 50 MHz to 3GHz.
 33. A plasma processing apparatus as defined in claim 24, whereinthe dielectric tube is a bolt screwed in a tap given to the metal bodyor the facing electrode.
 34. A plasma processing apparatus as defined inclaim 24, wherein the dielectric tube has a spot facing for screwdriveror wrench on a side of an inner wall of the vacuum chamber for rotatingand screwing the dielectric tube in the metal plate or the facingelectrode.
 35. A plasma processing apparatus as defined in claim 24,wherein the dielectric tube is protruded by 0.5 to 20 mm from a surfaceof the metal body or the facing electrode.
 36. A plasma processingapparatus as defined in claim 24, wherein the dielectric tube isprotruded by 1 to 10 mm from a surface of the metal body or the facingelectrode.
 37. A plasma processing apparatus as defined in claim 27 or28, wherein the dielectric tube is disposed such that it covers an edgeof a hole of the metal body or the facing electrode.
 38. A plasmaprocessing apparatus as defined in claim 24, wherein the hole of thedielectric tube is 0.2 to 2 mm in diameter.
 39. A plasma processingapparatus as defined in claim 24, wherein the hole of the dielectrictube is 0.4 to 0.8 mm in diameter.
 40. A plasma processing apparatus asdefined in claim 24, wherein a frequency of high-frequency power appliedto the plasma source, the substrate electrode or the facing electrode is50 MHz to 3 GHz.